General medical hospitals provide care for a disproportionate share of patients who abuse or are dependent upon substances. This group is among the most costly to treat and has the poorest medical and substance use outcomes. Hospitalization provides a unique opportunity to identify and motivate patients to address their substance use problems in that patients are: 1) accessible; 2) have time for an intervention; and 3) are often admitted for complications related to substance use that renders hospitalization a teachable moment. Brief interventions that increase motivation for substance abuse treatment are well suited for an inpatient medical setting but optimal methods for the implementation of such interventions are not well researched. We propose to use quantitative and qualitative methods to examine the effectiveness of three different implementation strategies for integrating motivational interviewing (MI) into the practice of physician assistants (PAs) working within Yale-New Haven Hospital's general medical hospitalist service. Specifically, we will randomize 30 PAs to one of three conditions: (1) a continuing medical education workshop that provides background and shows PAs how to conduct MI (the control condition, called SEE ONE); (2) a see one, do one apprenticeship model involving workshop training plus live supervision of bedside practice (DO ONE); and (3) ordering MI from CL after learning about it in a workshop (ORDER ONE). Following the respective MI trainings, each PA will be assessed for the provision of MI to 40 study-eligible inpatients, recruited by the research team after admission to our general medical units. Implementation issues will be explored qualitatively. Our primary aims are to assess: 1) the uptake of MI by PAs; 2) the integrity of MI when PAs use it on the medical units; and 3) the relative costs and cost-effectiveness of the three different implementation strategies.